N-(4-(5-Nitro-2-furyl)-2-thiazolyl) formamide (FANFT) is a potent and highly specific carcinogen for the bladder of rat and provides a potential model for the study of human bladder cancer. The metabolism of FANFT may include deformylation, ring hydroxylation and nitroreduction. Its activation may involve the formation of hydroxylaminofuran, conjugation of this metabolite with glucuronic acid, and transportation of this conjugate to the bladder, where free hydroxylaminofuran is regenerated and acts on the urothelial cells. The detoxication mechanism may involve the conjugation of hydroxylaminofuran with thiols, ring hydroxylation of nitrofuran, and synthesis and transformation of aminofuran. Based on this hypothesis, we propose to investigate tumorigenesis by FANFT and its prevention. To approach these: (1) the urinary metabolites of FANFT will be isolated and identified and their bacterial mutagenic activities ascertained; (2) rats will be fed FANFT and allopurinol, phenothiazine, cysteine, or 2,5-di-O-acetyl-D-glycosaccharo-(1 yields 4) (6 yields 3) dilactone (SLA). Urine will be collected, metabolites of FANFT analyzed, and beta-glucuronidase activity determined. The preventive effect of these dietary supplements on the induction of bladder tumors will be evaluated. The correlations of tumorigenesis with urinary metabolites of FANFT and beta-glucuronidase activity will be determined; (3) in vitro experiments will be done with rat organs, particularly liver and bladder, for the activation and interaction of FANFT with macromolecules. These explorations will contribute to the understanding of bladder tumorigenesis and prevention in experimental animals, and may be relevant to bladder carcinogens in the human environment.